Character frequencies in Java
Java interview exercise on Strings, difficulty 1 of 3. Solve it in the editor beside a worked example, or cold in Interview mode with the example hidden; the tests run the moment you do.
Write charFrequency(s) that returns a Map from each character in s to the number of times it occurs, in the order the characters first appear (a LinkedHashMap). Every character counts, spaces included; case is kept as it is.
Each exercise pairs a worked example with a twin problem to solve in a real editor; the tests run the moment you do. Interview mode hides the example: solve it from memory, without the hint or the solution, and it counts as solved cold. Progress is saved in your browser, and in your account if you sign in.